The alkaline earth metal nitrate that does not crystallise with water molecules, is: Ca(NO3)2, Ba(NO3)2, Mg(NO3)2, Sr(NO3)2
Mg(NO3)2
Sr(NO3)2
Ca(NO3)2
Ba(NO3)2
Solution:
Smaller in size of cation, more water molecules will crystallize. Due to its largest size of Ba2+ ion, Ba(NO3)2 doesn't crystallize with water molecules. Hence, the correct option is D.